U.S. patent application number 11/928694 was filed with the patent office on 2008-05-29 for substrate processing apparatus and substrate processing method.
Invention is credited to Katsuhiko Miya.
Application Number | 20080121252 11/928694 |
Document ID | / |
Family ID | 39462409 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080121252 |
Kind Code |
A1 |
Miya; Katsuhiko |
May 29, 2008 |
SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD
Abstract
DIW is supplied toward a surface of a substrate to form a lower
layer liquid film, which is then frozen to form a lower layer
frozen film. Further, DIW cooled down to a temperature at which the
lower layer frozen film will not melt is supplied toward a surface
of the lower layer frozen film to form an upper layer liquid film,
which is then frozen to form an upper layer frozen film in a
layered structure. DIW which is at room temperature is thereafter
supplied, thereby melting the entirety of the lower layer frozen
film and the upper layer frozen film to remove these films together
with particles off from the surface of the substrate.
Inventors: |
Miya; Katsuhiko; (Kyoto,
JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
US
|
Family ID: |
39462409 |
Appl. No.: |
11/928694 |
Filed: |
October 30, 2007 |
Current U.S.
Class: |
134/4 ;
134/105 |
Current CPC
Class: |
B08B 7/0092 20130101;
B08B 3/10 20130101; H01L 21/67051 20130101; H01L 21/6715
20130101 |
Class at
Publication: |
134/4 ;
134/105 |
International
Class: |
B08B 3/00 20060101
B08B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2006 |
JP |
2006-320443 |
Claims
1. A substrate processing apparatus, comprising: a liquid supplier
which supplies a liquid toward a surface of a substrate; and a
freezing unit which freezes a liquid film which is formed on the
substrate surface by the supply of the liquid performed by the
liquid supplier, wherein a supply of the liquid toward a surface of
a lower layer frozen film which is formed by the freezing of the
liquid film performed by the freezing unit and freezing of thus
supplied liquid are executed at least once to thereby form an upper
layer frozen film on top of the lower layer frozen film in a
layered structure, and then the entire frozen films formed on the
substrate surface are removed.
2. The substrate processing apparatus of claim 1, further
comprising a lower layer film thickness adjuster which adjusts a
thickness of the liquid film which is formed on the substrate
surface by the supply of the liquid performed by the liquid
supplier to a predetermined value.
3. The substrate processing apparatus of claim 1, further
comprising: a storage unit which stores a number of times to form
the upper layer frozen film in a layered structure; and a rewriting
unit which rewrites the number of times stored within the storage
unit in accordance with a predetermined substrate processing
condition, wherein the forming of the upper layer frozen film in a
layered structure is executed the number of times stored in the
storage unit.
4. The substrate processing apparatus of claim 1, wherein the
freezing unit includes: a cooling gas discharger which discharges a
cooling gas whose temperature is lower than the freezing point of
the liquid toward a local section of the substrate surface; and a
relative moving mechanism which relatively moves the cooling gas
discharger relative to the substrate and parallel to the substrate
surface, and wherein the relative moving mechanism relatively moves
the cooling gas discharger relative to the substrate while the
cooling gas discharger discharges the cooling gas, whereby the
respective frozen films are formed.
5. The substrate processing apparatus of claim 4, wherein the
liquid supplier includes a liquid supply pipe which supplies the
liquid and a liquid discharge nozzle which discharges the liquid
inside the liquid supply pipe toward the substrate, the freezing
unit further includes a gas supply pipe which guides the cooling
gas to the cooling gas discharger, and at least a part of the
liquid supply pipe and at least a part of the gas supply pipe are
disposed side by side in the vicinity of each other.
6. The substrate processing apparatus of claim 5, wherein the
liquid discharge nozzle and the cooling gas discharger are disposed
in the vicinity of each other, and the relative moving mechanism
relatively moves the liquid discharge nozzle and the cooling gas
discharger as one unit relative to the substrate.
7. The substrate processing apparatus of claim 1, wherein the
supply of the liquid toward the surface of the lower layer frozen
film is performed by the liquid supplier, and the liquid supplier
includes a temperature adjuster which cools down the liquid to a
temperature at which the supply of the liquid does not melt the
lower layer frozen film.
8. The substrate processing apparatus of claim 7, wherein the
liquid is purified water or deionized water, and the temperature
adjuster cools the liquid down to 0 through 2 degrees
centigrade.
9. The substrate processing apparatus of claim 1, comprising a
droplet supplier which discharges minute droplets of the liquid and
accordingly supplies the liquid toward the surface of the lower
layer frozen film.
10. The substrate processing apparatus of claim 9, wherein the
freezing of the liquid is executed while the droplet supplier
discharges minute droplets of the liquid toward the surface of the
lower layer frozen film.
11. A substrate processing method, comprising: a multiply-layered
frozen film forming step of repeating more than once a liquid
supplying and freezing step of supplying a liquid toward a
substrate surface and freezing thus supplied liquid, to thereby
form a frozen film with plural layers in a layered structure on the
substrate surface; and a removal step of removing the entire frozen
film with plural layers.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The disclosure of Japanese Patent Application No.
2006-320443 filed Nov. 28, 2006 including specification, drawings
and claims is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a substrate processing
apparatus and a substrate processing method which freeze a liquid
film formed on a surface of a substrate and removes the frozen
film, the substrate including various types such as semiconductor
wafers, glass substrates for photomask, glass substrates for liquid
crystal display, glass substrates for plasma display, substrates
for FED (field emission display), substrates for optical disks,
substrates for magnetic disks, and substrates for magnet-optical
disks (hereinafter called simply a "substrate").
[0004] 2. Description of the Related Art
[0005] Conventionally used is a technique of freezing a liquid film
as it is maintained adhering to a substrate surface by cooling a
substrate as one of a substrate processing. Particularly this
freezing technique is used as part of a substrate cleaning
processing. That is, as devices typified by semiconductors have
finer patterns, more advanced functions and higher precision, it
becomes increasingly difficult to remove fine contaminants such as
particles adhering to the substrate surface without destroying
patterns formed on the substrate surface. And so, particles
adhering to the substrate surface are removed in the following
manner utilizing the freezing technique described above.
[0006] First, a liquid film is formed on a substrate surface by
supplying liquid to the substrate surface. Subsequently, the liquid
film is frozen by cooling the substrate. Thus, a frozen film is
formed on the substrate surface to which particles adhere. Finally,
the frozen film is removed from the substrate surface, whereby the
particles are removed from the substrate surface together with the
frozen film.
[0007] In the apparatus described in JP-A-3-145130 for instance,
with a substrate housed inside a processing chamber, a removal
fluid such as steam or ultra-pure vapor is supplied to the
substrate surface, whereby a liquid film of the removal fluid is
formed on the substrate surface. Following this, cooling gas which
is cooler than the freezing temperature of the removal fluid is
injected into and circulated inside the processing chamber so that
the liquid film on the substrate surface is frozen and a frozen
film is produced on the entire substrate surface. The frozen film
is then thawed to remove particles adhering to the substrate
surface. Specifically, in the apparatus described in JP-A-3-145130,
the pressure which develops at the time of volume expansion upon
freezing of the liquid film and which works upon the particles
reduces adhesion force between the particles and the substrate,
whereby the particles are removed off from the surface of the
substrate.
SUMMARY OF THE INVENTION
[0008] By the way, an attempt to increase the pressure which
develops due to volume expansion upon freezing of the liquid film
and accordingly facilitate removal of the particles, the pressure
may become excessively large and lead to destruction of patterns or
otherwise damage the substrate. Hence, for favorable substrate
processing, it is necessary to consider both encouraged removal of
the particles and prevention of damage upon the substrate. However,
the apparatus described in JP-A-3-145130 does not provide
sufficient consideration on these.
[0009] The present invention has been made in light of the problems
above, and accordingly aims at providing a substrate processing
apparatus and a substrate processing method with which it is
possible to facilitate particle removal while preventing damage
upon a substrate.
[0010] According to a first aspect of the present invention, there
is provided a substrate processing apparatus, comprising: a liquid
supplier which supplies a liquid toward a surface of a substrate;
and a freezing unit which freezes a liquid film which is formed on
the substrate surface by the supply of the liquid performed by the
liquid supplier, wherein a supply of the liquid toward a surface of
a lower layer frozen film which is formed by the freezing of the
liquid film performed by the freezing unit and freezing of thus
supplied liquid are executed at least once to thereby form an upper
layer frozen film on top of the lower layer frozen film in a
layered structure, and then the entire frozen films formed on the
substrate surface are removed.
[0011] According to a second aspect of the present invention, there
is provided a substrate processing method, comprising: a
multiply-layered frozen film forming step of repeating more than
once a liquid supplying and freezing step of supplying a liquid
toward a substrate surface and freezing thus supplied liquid, to
thereby form a frozen film with plural layers in a layered
structure on the substrate surface; and a removal step of removing
the entire frozen film with plural layers.
[0012] The above and further objects and novel features of the
invention will more fully appear from the following detailed
description when the same is read in connection with the
accompanying drawing. It is to be expressly understood, however,
that the drawing is for purpose of illustration only and is not
intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a diagram showing a substrate processing apparatus
of a first embodiment of the invention.
[0014] FIG. 2 is a block diagram showing a control construction of
the substrate processing apparatus shown in FIG. 1.
[0015] FIG. 3 is a schematic diagram showing a structure of the
rinsing liquid supplier.
[0016] FIGS. 4A and 4B are diagrams showing a movement of the
cooling gas discharge nozzle.
[0017] FIGS. 5A through 5E are diagrams showing a processing to the
top surface Wf of the substrate W.
[0018] FIG. 6 is a flow chart of the operation in the substrate
processing apparatus shown in FIG. 1.
[0019] FIG. 7 is a drawing which shows the relationship between the
thickness of a liquid film of DIW on a surface of a substrate and
the particle removal rate, and the relationship between the film
thickness and a damage occurrence count.
[0020] FIG. 8 is a diagram showing a second embodiment of a
substrate processing apparatus according to the invention.
[0021] FIG. 9 is a block diagram which shows the control structure
of the substrate processing apparatus of FIG. 8.
[0022] FIG. 10 is a plan view showing a movement of the
mist-generating nozzle.
[0023] FIGS. 11A through 11D are diagrams showing processing to the
top surface Wf of the substrate W.
[0024] FIG. 12 is a flow chart showing an operation sequence of the
substrate processing apparatus shown in FIG. 8.
[0025] FIGS. 13A to 13C are diagrams showing a modification of
discharge of the rinsing liquid.
[0026] FIG. 14 is a diagram showing a modification in which a
structure for chemical cleaning is added to the apparatus of the
first embodiment.
[0027] FIG. 15 is a diagram showing a frozen film removal
processing in the apparatus shown in FIG. 14.
[0028] FIG. 16 is a diagram showing a modification in which a
structure for physical cleaning is added to the apparatus of the
first embodiment.
[0029] FIG. 17 is a diagram showing a structure of a two-fluid
nozzle.
[0030] FIG. 18 is a block diagram showing a control construction of
another modification of a substrate processing apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0031] FIG. 1 is a diagram showing a substrate processing apparatus
of a first embodiment of the invention. FIG. 2 is a block diagram
showing a control construction of the substrate processing
apparatus shown in FIG. 1. This substrate processing apparatus is a
single wafer type substrate processing apparatus that is used for
the cleaning processes for the purpose of removing contaminants
such as particles adhering to a top surface Wf and a rear surface
Wb of a substrate W such as semiconductor wafer. More specifically,
this substrate processing apparatus is an apparatus which forms a
liquid film on the top surface Wf of the substrate W, forms a lower
layer frozen film by freezing the liquid film, then forms an upper
layer frozen film on the top surface of the lower layer frozen film
in a layered structure, and then, removes whole of the frozen film
from the top surface Wf of the substrate W, whereby a cleaning
processing is performed to the substrate W.
[0032] This substrate processing apparatus includes a processing
chamber 1 which has a processing space inside in which a cleaning
processing is performed to the substrate W, and a control unit 4
which controls the entire apparatus. In the processing chamber 1, a
spin chuck 2, a cooling gas discharge nozzle 3, and a blocking
member 9 are provided. The spin chuck 2 holds the substrate W in an
approximately horizontally such that the top surface Wf of the
substrate W is directed toward above and rotates the substrate W.
The cooling gas discharge nozzle 3 discharges cooling gas for
freezing a liquid film toward the top surface Wf of the substrate W
held by the spin chuck 2. The blocking member 9 is disposed facing
the top surface Wf of the substrate W held by the spin chuck 2.
[0033] A disk-shaped spin base 23 is fixed by a fastening component
such as a screw to a top end portion of a central shaft 21 of the
spin chuck 2. The central shaft 21 is linked to a rotation shaft of
a chuck rotating mechanism 22 which contains a motor. The spin base
23 fixed to the central shaft 21 rotates about a rotation center A0
when the chuck rotating mechanism 22 is driven in response to an
operation command received from the control unit 4.
[0034] Plural chuck pins 24 for holding the substrate W at the rim
thereof are disposed upright in the vicinity of the rim of the spin
base 23. There may be three or more chuck pins 24 to securely hold
the disk-shaped substrate W, and the chuck pins 24 are arranged at
equal angular intervals along the rim of the spin base 23. Each of
the respective chuck pins 24 comprises a substrate support part
which supports the substrate W at the rim thereof from below and a
substrate holding part which presses the substrate W at the outer
peripheral edge surface thereof to hold the substrate W. Each chuck
pin 24 is structured so as to be capable of switching between a
pressing state that the substrate holding part presses the
substrate W at the outer peripheral edge surface thereof and a
released state that the substrate holding part stays away from the
outer peripheral edge surface of the substrate W.
[0035] The respective chuck pins 24 are in the released state while
the substrate W is being transferred to the spin base 23 but in the
pressing state for cleaning of the substrate W. When in the
pressing state, the respective chuck pins 24 hold the substrate W
at the rim thereof and keep the substrate approximately
horizontally at a predetermined distance from the spin base 23. The
substrate W is held with its top surface Wf directed toward above
and its rear surface Wb toward below. Meanwhile, in this
embodiment, fine patterns are formed on the top surface Wf of the
substrate W, which means that the top surface Wf is a
pattern-formed surface.
[0036] The blocking member 9 is in a form of a disk-shape which has
an opening at its center. The under surface of the blocking member
9 is a substrate-facing surface which faces the top surface Wf of
the substrate W approximately parallel, and the size of this
surface is equal to or greater than the diameter of the substrate
W. The blocking member 9 is attached approximately horizontally to
the lower end of a support shaft 91 which is shaped approximately
like a circular cylinder. An arm 92 extending in the horizontal
direction holds the support shaft 91 so that the support shaft 91
can rotate about a vertical axis which penetrates the center of the
substrate W. Further, a blocking-member rotating mechanism 93 and a
blocking-member elevating mechanism 94 are connected to the arm
92.
[0037] The blocking-member rotating mechanism 93 rotates the
support shaft 91 in response to an operation command from the
control unit 4 about the vertical axis which penetrates the center
of the substrate W. Further, the control unit 4 controls an
operation of the blocking-member rotating mechanism 93 to rotate
the blocking member 9 at about the same rotation speed in the same
direction as the substrate W in accordance with rotation of the
substrate W which is held by the spin chuck 2.
[0038] The blocking-member elevating mechanism 94 moves the
blocking member 9 toward the spin base 23, and conversely, away
therefrom in accordance with an operation command from the control
unit 4. Specifically, the control unit 4 controls an operation of
the blocking-member elevating mechanism 94 to move the blocking
member 9 upward to a separated position (position shown in FIG. 1)
above the spin chuck 2 upon loading and unloading the substrate W
into and from the substrate processing apparatus, whereas to move
the blocking member 9 downward to a specified facing position set
very close to the top surface Wf of the substrate W held by the
spin chuck 2 upon performing a predetermined processing to the
substrate W.
[0039] The support shaft 91 is formed hollow and accepts
penetration by a gas supply pipe 95 which extends to the opening of
the blocking member 9. The gas supply pipe 95 is connected with the
drying gas supplier 65. The drying gas supplier 65 supplies
nitrogen gas via the gas supply pipe 95 to a space which is formed
between the blocking member 9 and the top surface Wf of the
substrate W, during drying of the substrate W after cleaning.
Although nitrogen gas is supplied from the drying gas supplier 65
as a drying gas in this embodiment, air or another inert gas may be
supplied.
[0040] A rinsing liquid supply pipe 96 is inserted inside the gas
supply pipe 95. A bottom end portion of the rinsing liquid supply
pipe 96 extends to the opening of the blocking member 9, and a
rinsing liquid discharging nozzle 97 is disposed at a tip end of
the rinsing liquid supply pipe 96. Whereas, a top end portion of
the rinsing liquid supply pipe 96 is connected with a rinsing
liquid supplier 62. The rinsing liquid supplier 62 supplies a
rinsing liquid. As the rinsing liquid, deionized water (hereinafter
called "DIW") is used for instance in this embodiment.
[0041] FIG. 3 is a schematic diagram showing a structure of the
rinsing liquid supplier. A tank 621 stores DIW and is connected
with a DIW supply source (not shown) already installed in a plant
for instance via a supply pipe 62A in which a valve V1 is disposed.
A supply pipe 62B is for supplying DIW to outside from the tank
621, and a pump 622 and a temperature adjuster 623 are disposed in
the supply pipe 62B. The lower end of the supply pipe 62B is
disposed reaching DIW stored in the tank 621, while the upper end
of the supply pipe 62B branches into supply pipes 62C and 62D. A
valve V2 is disposed in the supply pipe 62C, and the lower end of
the supply pipe 62C is disposed sticking into inside the tank 621.
Meanwhile, a filter F1 is disposed in the supply pipe 62D. The top
end of the supply pipe 62D branches out into the rinsing liquid
supply pipe 96 described above in which a valve V31 is disposed and
a liquid supply pipe 25 described later in which a valve V32 is
disposed. Hence, it is possible to feed DIW into the rinsing liquid
supply pipe 96 and the liquid supply pipe 25 individually from each
other or simultaneously. The temperature adjuster 623 cools down
DIW in response to an operation command received from the control
unit 4. The temperature adjuster 623 cools down the DIW to a
temperature at which a frozen film does not melt when the DIW is
supplied to the surface of the frozen film, the temperature being
not more than 5 degrees centigrade for instance in this embodiment.
Cooling down to an even lower temperature of 2 degrees centigrade
or below is preferable for more secure prevention of melting of the
frozen film. The temperature adjuster 623 maintains DIW at 0
degrees centigrade or a higher temperature, which prevents DIW from
freezing.
[0042] In a structure like this, DIW at room temperature is
supplied to the tank 621 from the DIW supply source when the valve
V1 is opened from the state that the valves V1, V2, V31 and V32 are
closed. Meanwhile, when the valve V2 is opened with the valves V31
and V32 closed and the pump 622 and the temperature adjuster 623
operate, the temperature adjuster 623 cools down DIW while the DIW
circulates through the tank 621 and the supply pipes 62B and 62C.
When the valve V2 is closed and the valve V31 is opened, thus
cooled DIW is supplied toward the rinsing liquid supply pipe 96
after filtered by the filter F1. The cooled DIW supplied to the
rinsing liquid supply pipe 96 is discharged toward the top surface
Wf of the substrate W from the rinsing liquid discharging nozzle
97, whereby a lower layer liquid film 11f and an upper layer liquid
film 12f (FIGS. 5A and 5C) are formed. When the valve V2 is closed
and the valve V32 is opened with the temperature adjuster 623 not
operating and the pump 622 alone working, DIW at room temperature
is supplied toward the liquid supply pipe 25 after filtered by the
filter F1, and discharged toward the rear surface Wb of the
substrate W from a liquid discharging nozzle 27. In this
embodiment, the rinsing liquid supplier 62, the rinsing liquid
supply pipe 96 and the rinsing liquid discharging nozzle 97 thus
correspond to the "liquid supplier" of the invention.
[0043] Description is to be continued by referring back to FIG. 1.
The central shaft 21 of the spin chuck 2 is formed by a hollow
shaft having a cylindrical cavity. A cylindrical liquid supply pipe
25 for supplying a liquid to the rear surface Wb of the substrate W
is inserted in the central shaft 21. The liquid supply pipe 25
extends to a position close to the rear surface Wb which is in the
under surface side of the substrate W which is held by the spin
chuck 2, and a tip end of the liquid supply pipe 25 mounts a liquid
discharging nozzle 27 which discharges the liquid toward a central
area in the bottom surface of the substrate W. The liquid supply
pipe 25 is connected to the rinsing liquid supplier 62. When DIW is
supplied from the rinsing liquid supplier 62, the DIW is discharged
from the liquid discharging nozzle 27 via the liquid supply pipe 25
toward the rear surface Wb of the substrate W and the rear surface
Wb is rinsed.
[0044] A clearance between the inner wall surface of the central
shaft 21 and the outer wall surface of the liquid supply pipe 25
forms a gas supply passage 29 which is in a form of a ring in
horizontal section. This gas supply passage 29 is connected to the
drying gas supplier 65, so that nitrogen gas is supplied from the
drying gas supplier 65 via the gas supply passage 29 to a space
formed between the spin base 23 and the rear surface Wb of the
substrate W.
[0045] A motor 31 is disposed at a place outward from the spin
chuck 2 in a circumferential direction. A rotary shaft 33 is
connected to the motor 31, an arm 35 extending horizontally is
connected to the rotary shaft 33, and the cooling gas discharge
nozzle 3 is attached to the end of the arm 35. When the motor 31 is
driven in accordance with an operation command from the control
unit 4, the arm 35 swings around the rotary shaft 33.
[0046] FIGS. 4A and 4B are diagrams showing a movement of the
cooling gas discharge nozzle. FIG. 4A is a side view of the cooling
gas discharge nozzle and FIG. 4B is a plan view thereof. When the
motor 31 is driven to swing the arm 35 based on the operation
command from the control unit 4, the cooling gas discharge nozzle 3
moves along a moving trajectory T while facing the top surface Wf
of the substrate W as shown in FIG. 4B. The moving trajectory T is
a trajectory from a rotational center position Pc toward an edge
position Pe. At this stage, the rotational center position Pc is
located over the substrate W and above the rotation center A0 of
the substrate W, and the edge position Pe is located above the
outer circumferential edge of the substrate W. That is, the motor
31 relatively moves the cooling gas discharge nozzle 3 relative to
the substrate W and parallel to the top surface Wf of the substrate
W. Further, the cooling gas discharge nozzle 3 is movable to a
standby position Ps which is located on an extended line of the
moving trajectory T and away from the opposed position to the
substrate W.
[0047] The cooling gas discharge nozzle 3 is connected to a cooling
gas supplier 64. The cooling gas supplier 64 supplies cooling gas
to the cooling gas discharge nozzle 3 in accordance with an
operation command from the control unit 4. When the cooling gas
discharge nozzle 3 is positioned facing the top surface Wf of the
substrate W, and the cooling gas is supplied to the cooling gas
discharge nozzle 3 from the cooling gas supplier 64, the cooling
gas is discharged from the cooling gas discharge nozzle 3 toward
the top surface Wf of the substrate W locally. And, when the motor
31 moves the cooling gas discharge nozzle 3 along the moving
trajectory T while the substrate W is rotated by the spin chuck 2
in accordance with a operation command from the control unit 4, in
a state that the cooling gas is discharged from the cooling gas
discharge nozzle 3, the cooling gas is supplied to the entire top
surface Wf of the substrate W. Therefore, the entire liquid film
11f formed on the top surface Wf of the substrate W by the
discharge of DIW from the rinsing liquid discharge nozzle 97 is
frozen to form a frozen film 13f on the entire top surface Wf of
the substrate W.
[0048] The height of the cooling gas discharge nozzle 3 from the
top surface Wf of the substrate W is different depending upon the
supplying amount of the cooling gas, but may be set not more than
50 mm for instance and preferably about several mm. Such height of
the cooling gas discharge nozzle 3 from the top surface Wf of the
substrate W and the supplying amount of the cooling gas is
determined experimentally from (1) a viewpoint of giving cold
energy the cooling gas has to the liquid film 11f efficiently, and
(2) a viewpoint of freezing the liquid film 11f stably without
distorting the surface of the liquid film 11f by the cooling
gas.
[0049] A temperature of the cooling gas is below the freezing point
of the liquid which composes the liquid film 11f formed on the top
surface Wf of the substrate W, that is, below the freezing point of
DIW in this embodiment. The cooling gas is produced by flowing
nitrogen gas in a pipe which is disposed in a liquid nitrogen
stored in a tank, for example, and is cooled at -100 degrees
centigrade for instance. Meanwhile, oxygen gas, clean air, and the
like may be used instead of nitrogen gas. Since such cooling gas is
used, it is easy to eliminate contaminants contained in the cooling
gas by a filter and the like before supplying the gas to the top
surface Wf of the substrate W, which makes it possible to prevent
from contaminating the top surface Wf of the substrate W in
freezing the liquid film 11f. Thus, in this embodiment, the cooling
gas discharge nozzle 3 corresponds to the "cooling gas discharger"
of the invention, and the motor 31 corresponds to the "relative
moving mechanism" of the invention.
[0050] The cleaning operation in the substrate processing apparatus
having the structure above will now be described with reference to
FIGS. 5A through 5E and 6. FIGS. 5A through 5E are diagrams showing
a processing to the top surface Wf of the substrate W. FIG. 5A
shows a lower layer liquid film forming processing, FIG. 5B shows a
lower layer liquid film freezing processing, FIG. 5C shows an upper
layer liquid film forming processing, FIG. 5D shows an upper layer
liquid film freezing processing, and FIG. 5E shows a frozen film
removal processing. Further, FIG. 6 is a flow chart of the
operation in the substrate processing apparatus shown in FIG. 1. In
this apparatus, upon loading of the substrate W into inside the
apparatus, the control unit 4 controls the respective sections of
the apparatus and cleaning processing is performed upon the
substrate W. First, the substrate W is loaded into inside the
processing chamber 1 with the top surface Wf of the substrate W
directed toward above, and held by the spin chuck 2 (Step S1).
Meanwhile, the blocking member 9 is located at the separated
position, which obviates interference with the substrate W.
[0051] As the spin chuck 2 holds an unprocessed substrate W, the
blocking member 9 descends to the opposed position and becomes
positioned close to the top surface Wf of the substrate W. The top
surface Wf of the substrate W is therefore covered as it is located
in the vicinity of the substrate-facing surface of the blocking
member 9, and is blocked from the surrounding atmosphere around the
substrate W. The control unit 4 then activates the chuck rotating
mechanism 22 to rotate the spin chuck 2, and activates the rinsing
liquid supplier 62 to discharge cooled DIW from the rinsing liquid
discharging nozzle 97 to supply the DIW to the top surface Wf of
the substrate W. Centrifugal force which develops as the substrate
W rotates acts upon the DIW supplied to the top surface Wf of the
substrate W, and the DIW spreads uniformly outward in the radial
direction of the substrate W and is partially shaken off from the
substrate. This controls the thickness of the liquid film uniform
all across the entire top surface Wf of the substrate W, and forms
the lower layer liquid film 11f which has a predetermined thickness
D1 all over the top surface Wf of the substrate W as shown in FIG.
5A (Step S2). At this stage, the control unit 4 adjusts the number
of rotation of the spin chuck 2, whereby the lower layer liquid
film 11f which has a predetermined thickness D1 is formed. The
thickness of the lower layer liquid film 11f will be described in
detail hereinafter.
[0052] When the lower layer liquid film forming processing is thus
finished, the control unit 4 positions the blocking member 9 at the
separated position and moves the cooling gas discharge nozzle 3 to
the rotational center position Pc from the stand-by position Ps.
While discharging the cooling gas toward the top surface Wf of the
rotating substrate W, the cooling gas discharge nozzle 3 then moves
gradually toward the edge position Pe of the substrate W. As a
result, as shown in FIG. 5B, of the surface region of the top
surface Wf of the substrate W, an area where the liquid film 11f
has been frozen expands toward the periphery edge from the center
of the top surface Wf of the substrate W, whereby the lower layer
frozen film 13f is formed all over the top surface Wf of the
substrate W (Step S3). At this stage, since the DIW which composes
the lower layer liquid film 11f is cooled to a low temperature by
the temperature adjuster 623, it is possible to form the lower
layer frozen film 13f in a short time.
[0053] Meanwhile, it is possible to suppress an uneven distribution
of the liquid film thickness and accordingly form the lower layer
frozen film 13f all over the top surface Wf of the substrate W by
rotating the substrate W while the cooling gas discharge nozzle 3
is moved. However, if the substrate W rotates at an excessively
high speed, airflows developed by the rotations of the substrate W
may diffuse the cooling gas which is discharged from the cooling
gas discharge nozzle 3 and the efficiency of freezing the liquid
film may worsen. Therefore, the rotation speed of the substrate W
in performing the lower layer liquid film freezing processing and
the upper layer liquid film freezing processing which is described
hereinafter is set to 1 through 300 rpm for example in this
embodiment. Further, it is more preferable that the rotation speed
of the substrate W is determined considering the traveling speed of
the cooling gas discharge nozzle 3, the temperature and the flow
rate of the discharged gas and the thickness of the liquid film as
well.
[0054] When the freezing of the liquid film is completed, the
control unit 4 moves the cooling gas discharge nozzle 3 to the
stand-by position Ps and positions the blocking member 9 at the
opposed position. Then, the control unit 4, similarly to Step S2,
activates the chuck rotating mechanism 22 to rotate the spin chuck
2, and activates the rinsing liquid supplier 62 to discharge cooled
DIW from the rinsing liquid discharging nozzle 97 to supply the DIW
to the top surface Wf of the substrate W. Hence, the thickness of
the liquid film is made uniform all across the entire top surface
Wf of the substrate W, and the upper layer liquid film 12f which
has a predetermined thickness D2 is formed on the lower layer
frozen film 13f in a layered structure all over the top surface Wf
of the substrate W as shown in FIG. 5C (Step S4). At this stage,
since the DIW is cooled by the temperature adjuster 623, the lower
layer frozen film 13f does not melt.
[0055] After the upper layer liquid film forming processing is
finished, the control unit 4, similarly to Step S3, positions the
blocking member 9 at the separated position and moves the cooling
gas discharge nozzle 3 to the rotational center position Pc from
the stand-by position Ps. While discharging the cooling gas toward
the top surface Wf of the rotating substrate W, the cooling gas
discharge nozzle 3 then moves gradually toward the edge position Pe
of the substrate W. As a result, as shown in FIG. 5D, of the
surface region of the top surface Wf of the substrate W, an area
where the upper liquid film 12f has been frozen expands toward the
periphery edge from the center of the top surface Wf of the
substrate W, whereby the upper layer frozen film 14f is formed all
over the top surface Wf of the substrate W (Step S5). At this
stage, since the DIW which composes the upper layer liquid film 12f
is cooled by the temperature adjuster 623 at such a temperature
that the lower layer frozen film 13f is not melted, it is possible
to form the upper layer frozen film 14f in a short time.
[0056] Subsequently, the determination is made whether the number
of layer of the upper layer frozen film is equal to a predetermined
value or not (Step S6). When the number of layer is not equal to
the predetermined value (NO at Step S6), Steps S4 and S5 are
executed repeatedly, whereas the number of layer is equal to the
predetermined value (YES at Step S6), the operation proceeds to
Step 7. In this embodiment, the predetermined value is 1 as shown
in FIGS. 5A through 5E.
[0057] At Step S7, the control unit 4 moves the cooling gas
discharge nozzle 3 to the stand-by position Ps and positions the
blocking member 9 at the opposed position. The rinsing liquid
discharging nozzle 97 supplies the DIW to the top surface Wf of the
substrate W before the lower layer frozen film 13f and the upper
layer frozen film 14f have been melted. At this time, the control
unit 4 stops the operation of the temperature adjuster 623, whereby
the DIW at room temperature is supplied to the substrate W. This
causes whole of the frozen films 13f and 14f on the top surface Wf
of the substrate W to be melted as shown in FIG. 5E. Further, the
centrifugal force which develops as the substrate W rotates acts
upon the frozen films 13f and 14f, and upon the DIW supplied to the
top surface Wf of the substrate W. In consequence, the frozen films
13f and 14f containing the particles are removed from the top
surface Wf of the substrate W and are discharged to outside the
substrate.
[0058] Meanwhile, at the frozen film removal processing, it is
preferable that the blocking member 9 rotates as the substrate W
rotates. The liquid component adhering to the blocking member 9 is
therefore shaken off, and it is possible to prevent the mist-like
liquid from intruding into the space formed between the blocking
member 9 and the top surface Wf of the substrate W from around the
substrate.
[0059] When the frozen film removal processing is thus finished,
the determination is made whether the cleaning processing of the
substrate W is completed or not (Step S8). When it is determined
that the processing is completed (YES at Step S8), drying
processing of the substrate W is carried out (Step S9). On the
other hand, when it is determined that the processing is not
completed (NO at Step S8), the routine is returned to Step S2 and
DIW is supplied to form the lower layer liquid film, and Steps S2
through S7 are executed repeatedly hereinafter. To be more
specific, depending on the surface condition of the top surface Wf
of the substrate W which is a surface-to-be-processed or the
particle diameters and the type of particles which must be removed,
the particles may not be removed sufficiently off from the top
surface Wf of the substrate W through one cleaning. In such a case,
the determination is made that the processing is not completed.
Through repeated execution of cleaning processing over a
predetermined number of times, the particles are removed off from
the top surface Wf of the substrate W. The number of re-executions
may be determined in advance as a processing recipe, and the
cleaning processing may be repeated over thus determined number of
times according to a processing recipe which is chosen
appropriately.
[0060] At Step S9, the control unit 4 increases the rotation speeds
of the motors for the chuck rotating mechanism 22 and the
blocking-member rotating mechanism 93 and makes the substrate W and
the blocking member 9 rotate at high speeds to execute drying
processing of the substrate W. During this drying processing,
nitrogen gas is supplied from the drying gas supplier 65 via the
gas supply pipes 95 and 29, to thereby make a nitrogen gas
atmosphere in the space which is sandwiched between the blocking
member 9 and the top surface Wf of the substrate W and the space
which is sandwiched between the spin base 23 and the rear surface
Wb of the substrate W. This facilitates drying of the substrate W
and shortens the drying time. After the drying processing, the
substrate W stops rotating and the processed substrate W is taken
out from the processing chamber 1 (Step S7). Thus, in this
embodiment, Steps S2 and S3, and Steps S4 and S5 correspond to the
"liquid supplying and freezing step" of the invention, and these
Steps S2 through S5 correspond to the "multiply-layered frozen film
forming step" of the invention. Further, Step S7 corresponds to the
"removal step" of the invention.
[0061] The effect of forming the upper layer frozen film on top of
the lower layer frozen film in a layered structure will now be
described with reference to FIG. 7. FIG. 7 is a drawing which shows
the relationship between the thickness of a liquid film of DIW
(hereinafter referred to as the "film thickness") on a surface of a
substrate and the particle removal rate, and the relationship
between the film thickness and a damage occurrence count. That is,
FIG. 7 shows the particle removal rate and the damage occurrence
count in the apparatus of FIG. 1 which has formed lower layer
liquid films having various film thicknesses, frozen the lower
layer liquid films, and then removed the lower layer frozen films.
In FIG. 7, denoted at the solid line Q1 with the square mark
.diamond-solid. is the relationship between the film thickness and
the particle removal rate P, while denoted at the solid line Q2
with the square mark .box-solid. is the relationship between the
film thickness and the damage occurrence count N.
[0062] At this stage, the natures of the particle removal rate P
and the damage occurrence count N will be described respectively.
The higher the particle removal rate P is, the better, which is
needless to mention. As denoted at the solid line Q1 in FIG. 7, the
particle removal rate P gradually increases as the film thickness
increases. It is thus understood that as the film thickness
increases, the substrate is cleaned more favorably. In contrast,
the substrate is excluded as a defective and treated as non-usable
when the damage occurrence count N denoted at the solid line Q2
exceeds 0. In short, N=0 is essential to the substrate processing.
Since N exceeds 0 beyond the film thickness T1, it is understood
that the film thickness needs be T1 or lower.
[0063] The particle removal rate P thus increases in accordance
with an increase of the film thickness and the damage occurrence
count N exceeds 0, that is, N>0, when the film thickness exceeds
the predetermined threshold value T1, for the following reason.
That is, when the liquid film freezing processing which freezes the
liquid film formed on the top surface Wf of the substrate W is
executed, the liquid entering between the top surface Wf of the
substrate W and the particles is frozen, whereby the volume is
expanded. For example, when purified water of 0 degrees centigrade
becomes ice of 0 degrees centigrade, the volume thereof increases
by about 1.1 times. The pressure generated by the volume expansion
acts on the particles, whereby the particles move away extremely
short distances from the top surface Wf of the substrate W. This
reduces the adherence between the top surface Wf of the substrate W
and the particles and further separates the particles from the top
surface Wf of the substrate W. When this occurs, even though there
are fine patterns formed on the top surface Wf of the substrate W,
when the pressure upon the patterns owing to the cubical expansion
is equal in all directions, the force applied upon the patterns
gets offset. Hence, it is possible to preferably remove the
particles off from the top surface Wf of the substrate W, without
damaging the substrate W such as peeling off or destroying the
patterns.
[0064] Since the volume increase attributable to the volume
expansion accelerates as the film thickness increases, the pressure
acting upon the particles increases and hence the particle removal
rate also increases. Meanwhile, upon increase of the film thickness
and hence the pressure acting upon the particles, when the pressure
applied upon the particles varies locally depending upon the
application direction, the different pressures will not offset each
other, and therefore, the substrate W will be damaged. Noting this,
the thickness D1 of the lower layer liquid film 11f formed on the
top surface Wf of the substrate W is D1=T1.times.0.8 for instance
in this embodiment. In other words, the film thickness D1 is set to
80% of the film thickness threshold value T1 which causes the
damage occurrence count N to exceed 0, to thereby ensure that the
damage occurrence count N is always 0 without fail. The film
thickness of the lower layer liquid film 11f is adjusted by the
adjustment of the number of revolution of the spin chuck 2 which is
performed by the control of the operation of the chuck rotating
mechanism 22. In this embodiment, the chuck rotating mechanism 22
thus corresponds to the "lower layer film thickness adjuster" of
the invention.
[0065] At this stage, as denoted at the solid line Q1 in FIG. 7,
the particle removal rate P satisfies P=P1, which means that with a
single layer frozen film formation, it is not possible to attain
the particle removal rate which is greater than P1 in order to
securely prevent the damage occurrence count N from exceeding 0. In
connection with this, consideration will now be given on an
instance of forming the upper layer frozen film 14f, which is
obtained by freezing the upper layer liquid film 12f having the
film thickness D2, on top of the lower layer frozen film 13f which
is obtained by freezing the lower layer liquid film 11f having the
film thickness D1 in the manner described above. The film thickness
of the upper layer liquid film 12f as well is adjusted by the
adjustment of the number of revolution of the spin chuck 2 which is
performed by the control of the operation of the chuck rotating
mechanism 22.
[0066] In this instance, while the film thickness of the frozen
films as a whole is (D1+D2), the pressure working upon particles
owing to the upper layer frozen film 14f works indirectly via the
lower layer frozen film 13f. Hence, an increase of the pressure
upon particles due to a volume expansion of the upper layer frozen
film 14f is smaller than an increase of the pressure attributable
to a single layer frozen film having the film thickness (D1+D2)
over the pressure attributable to a single layer frozen film having
the film thickness D1. The particle removal rate with the upper
layer frozen film 14f formed on top of the lower layer frozen film
13f in a layered structure is therefore down to P2 which is smaller
than the value denoted at the solid line Q1 which corresponds to
the film thickness (D1+D2). In the meantime, the damage occurrence
count N is maintained at 0 in this instance although the film
thickness (D1+D2) is greater than the threshold value T1. That is,
where the upper layer frozen film 14f is formed on the lower layer
frozen film 13f in a layered structure, the film thickness
threshold value which causes the damage occurrence count N to
exceed 0 changes to T2 from T1, as shown in FIG. 7.
[0067] Further consideration will now be given on an instance of
forming an upper layer frozen film, which is obtained by freezing
an upper layer liquid film having the film thickness D3, on top of
the upper layer frozen film 14f, namely, an instance that the
predetermined value at Step S6 in FIG. 6 is 2. In this instance,
while the film thickness of the frozen films as a whole is
(D1+D2+D3), the pressure working upon particles owing to this upper
layer frozen film in the area where the film thickness is D3 works
indirectly via the lower layer frozen film 13f and further via the
upper layer frozen film 14f.
[0068] Hence, an increase of the pressure upon particles due to a
volume expansion of this upper layer frozen film is even smaller
than that arising due to a single layer frozen film. The particle
removal rate is therefore down to P3 which is smaller than the
value denoted at the solid line Q1 which corresponds to the film
thickness (D1+D2+D3). In the meantime, the damage occurrence count
N is maintained at 0 in this instance although the film thickness
(D1+D2+D3) is greater than the threshold value T2 described above.
That is, where two upper layer frozen films are formed on the lower
layer frozen film 13f in a layered structure, the film thickness
threshold value which causes the damage occurrence count N to
exceed 0 shifts further to T3 which is greater than T2, as shown in
FIG. 7.
[0069] As described above, according to this embodiment, since the
upper layer frozen film 14f is superimposed in a layered structure
on top of the lower layer frozen film 13f which is formed on the
surface Wf of the substrate W, and the frozen films 13f and 14f as
a whole are melted and accordingly removed, it is possible to
enhance the particle removal rate while preventing damage upon the
substrate W. In addition, it is possible to prevent melting of the
lower layer frozen film 13f before forming the upper layer frozen
film 14f on top of the lower layer frozen film 13f in a layered
structure, since for the purpose of superimposing the upper layer
frozen film 14f, DIW supplied onto the lower layer frozen film 13f
is cooled to a temperature at which the lower layer frozen film 13f
will not be melted, the temperature being 5 degrees centigrade or
lower for instance.
[0070] Further, according to this embodiment, it is possible to
shorten the time needed to form the lower layer frozen film 13f and
the upper layer frozen film 14f since the temperature adjuster 623
cools DIW supplied onto the substrate W for the purpose of forming
the lower layer liquid film 11f and the upper layer liquid film 12f
down to 5 degrees centigrade or below for example. That is, an
experiment conducted by the inventor has identified that the time
needed for freezing a liquid film is mostly used to cool down the
temperature of the liquid which composes the liquid film to the
vicinity of the freezing point. Noting this, in this embodiment,
the DIW supplied onto the substrate W is cooled in advance. Since
this shortens the time needed to decrease the temperature of the
lower layer liquid film 11f and the upper layer liquid film 12f
down to near the freezing point, it is possible to shorten the time
needed to freeze the liquid films. The time needed for the cleaning
processing is consequently shortened, which improves the throughput
of the substrate processing.
[0071] Further, in this embodiment, the cooling gas discharge
nozzle 3 discharges, toward a local section of the top surface Wf
of the substrate W, the cooling gas whose temperature is lower than
the freezing point of the liquid which composes the lower layer
liquid film 11f and the upper layer liquid film 12f formed on the
top surface Wf of the substrate W. The cooling gas discharge nozzle
3 then moves between the rotational center position Pc of the
substrate W and the edge position Pe of the substrate W while the
substrate W remain rotating, whereby the lower layer frozen film
13f and the upper layer frozen film 14f are formed all over the top
surface Wf of the substrate W. This limits a section receiving
supply of the cooling gas to a very narrow area on the top surface
Wf of the substrate W, which in turn minimizes a decrease of the
temperatures of the substrate peripheral members such as the spin
chuck 2. It is therefore possible to form the lower layer frozen
film 13f and the upper layer frozen film 14f all over the top
surface Wf of the substrate W while suppressing deterioration of
the substrate peripheral members. As a result, even when the
substrate peripheral members are made of a chemical-resistant resin
material with which it is hard to secure the resistance against
cold energy, degradation of the material of the substrate
peripheral members due to cold energy can be suppressed.
[0072] Further, according to this embodiment, it is possible to
repeatedly perform the liquid film forming processing, the liquid
film freezing processing and the frozen film removal processing
inside the same processing chamber 1 for the predetermined times.
It is therefore possible to securely remove off from the top
surface Wf of the substrate W those particles which can not be
removed from the top surface Wf of the substrate W through only
single execution of the liquid film freezing processing and the
frozen film removal processing.
[0073] Further, according to this embodiment, execution of the
frozen film removal processing is started before the lower layer
frozen film 13f and the upper layer frozen film 14f have been
melted. This makes it possible to prevent particles fallen off from
the top surface Wf of the substrate W at the liquid film freezing
processing from re-adhering to the top surface Wf of the substrate
W again as the frozen film gets melted. It is therefore possible to
efficiently remove the particles together with the frozen film off
from the top surface Wf of the substrate W through execution of the
frozen film removal processing, which is advantageous in improving
the particle removal rate.
[0074] In other words, the embodiment comprises a liquid supplier
which supplies a liquid toward a surface of a substrate, and a
freezing unit which freezes a liquid film which is formed on the
substrate surface by the supply of the liquid performed by the
liquid supplier. And in the embodiment, a supply of the liquid
toward a surface of a lower layer frozen film which is formed by
the freezing of the liquid film performed by the freezing unit and
freezing of thus supplied liquid are executed at least once to
thereby form an upper layer frozen film on top of the lower layer
frozen film in a layered structure, and then the entire frozen
films formed on the substrate surface are removed.
[0075] According to this structure, the liquid supplier supplies
the liquid toward the substrate surface and the freezing unit
freezes the liquid film formed on the substrate surface as a result
of the supply of the liquid. This is followed by supply of the
liquid toward a surface of the lower layer frozen film formed as a
result of the liquid film freezing performed by the freezing unit
and freezing of thus supplied liquid for at least one time, so that
the upper layer frozen film is formed on top of the lower layer
frozen film in a layered structure. The frozen film consisting of
at least two layers is consequently formed on the substrate
surface, and the entire frozen film is removed.
[0076] Further, the embodiment comprises a multiply-layered frozen
film forming step of repeating more than once a liquid supplying
and freezing step of supplying a liquid toward a substrate surface
and freezing thus supplied liquid, to thereby form a frozen film
with plural layers in a layered structure on the substrate surface,
and a removal step of removing the entire frozen film with plural
layers.
[0077] According to this structure, the liquid supplying and
freezing step of supplying the liquid toward the substrate surface
and freezing thus supplied liquid is repeated multiple times, to
thereby form the frozen film with plural layers in a layered
structure on the substrate surface, and then, the entire frozen
film with plural layers formed on the substrate surface is
removed.
[0078] By the way, through various experiments, the inventor found
that as the thickness of a liquid film increases, the particle
removal rate increases and that when the thickness of a liquid film
exceeds a certain value, a substrate is damaged. An increase of the
particle removal rate is believed to be because the pressure which
develops due to volume expansion upon freezing of the liquid film
and acts upon particles increases as the thickness of a liquid film
increases. Meanwhile, it is considered that the reason why damage
occurs is because the pressure acts on not only the particles but a
surface of the substrate as well and therefore as the thickness of
the liquid film exceeds a certain value, the pressure becomes
excessive and adversely affects the substrate surface.
[0079] In light of this, the embodiment forms a frozen film
consisting of at least two layers, namely, forms a frozen film with
plural layers. The film thickness is larger than where there only
is a frozen film with a first layer, which increases the pressure
which develops due to volume expansion of the liquid film
associated with freezing of the liquid film and acts upon
particles. It is thus possible to enhance the particle removal rate
than where a frozen film with a first layer alone is formed.
Meanwhile, since the pressure which acts on the substrate surface
from a frozen film of a second layer indirectly works via the
frozen film of the first layer, the pressure which develops due to
volume expansion and acts on the substrate surface increases less
as compared with the value of the pressure due to the frozen film
of the first layer. Further, as for the pressures owing to a frozen
film of a third layer and subsequent layers for instance, since the
pressures act via the frozen films of the lower layers, the
pressures increase even less. It is hence possible to avoid
damaging of the substrate because of the pressures from the frozen
film of the second layer and the subsequent layers. Thus, according
to the embodiment, as the number of the layers which form the upper
layer frozen film for example is adjusted, it is easy to adjust the
pressure which acts on particles and the substrate surface, and it
is possible to facilitate removal of the particles while preventing
damaging of the substrate.
[0080] Further, the embodiment comprises a lower layer film
thickness adjuster which adjusts a thickness of the liquid film
which is formed on the substrate surface by the supply of the
liquid performed by the liquid supplier to a predetermined value.
Therefore, the thickness of a liquid film which is formed on the
substrate surface by the supply of the liquid by the liquid
supplier is adjusted to the predetermined value. Here, the
predetermined value may be a value which is sufficiently different
from the threshold value which starts causing damaging of the
substrate, a value which is about 80% of this threshold value for
instance. This makes it possible to securely prevent damaging of
the substrate.
[0081] Further, in the embodiment, the freezing unit includes a
cooling gas discharger which discharges a cooling gas whose
temperature is lower than the freezing point of the liquid toward a
local section of the substrate surface, and a relative moving
mechanism which relatively moves the cooling gas discharger
relative to the substrate and parallel to the substrate surface.
And, the relative moving mechanism relatively moves the cooling gas
discharger relative to the substrate while the cooling gas
discharger discharges the cooling gas, whereby the respective
frozen films are formed.
[0082] According to this structure, the cooling gas discharger
discharges the cooling gas whose temperature is lower than the
freezing point of the liquid locally toward the substrate surface.
While the cooling gas discharger discharges the cooling gas, the
relative moving mechanism relatively moves the cooling gas
discharger relative to the substrate and parallel to the substrate
surface, thereby forming the lower layer frozen film and forming
the upper layer frozen film in a layered structure. That is, as the
relative movement progresses, an area where the liquid, of the
liquid on the substrate, is frozen spreads, and the frozen film is
formed on the entire surface of the substrate. Since a section to
which the cooling gas is supplied is thus limited to a partial
region in the substrate surface, it is possible to minimize a
decrease of the temperature of a member which is disposed around
the substrate, a member for holding the substrate for instance.
Hence, it is possible to suppress deterioration of such
members.
[0083] Further, in the embodiment, the supply of the liquid toward
the surface of the lower layer frozen film is performed by the
liquid supplier, and the liquid supplier includes a temperature
adjuster which cools down the liquid to a temperature at which the
supply of the liquid does not melt the lower layer frozen film.
According to this structure, the liquid is supplied toward the
surface of the lower layer frozen film by the liquid supplier which
includes the temperature adjuster which cools down the liquid to a
temperature at which the supply of the liquid does not melt the
lower layer frozen film. Hence, it is possible to securely prevent
the lower layer frozen film from melting, which makes it possible
to favorably form the upper layer frozen film in a layered
structure. In addition, the liquid supplier can be used to form
both the lower layer frozen film and the upper layer frozen film in
a layered structure, which in turn reduces the number of parts and
simplifies the structure of the apparatus.
[0084] Further, in the embodiment, the liquid is deionized water.
Consequently, when the temperature adjuster cools down the
temperature of the liquid to 0 through 2 degrees centigrade, it is
preferable that the liquid does not freeze since the temperature
thereof is not less than 0 degrees centigrade. Further, it is also
preferable that the melting of the lower layer is securely
prevented since the liquid is cooled down to 2 degrees centigrade
or below.
Second Embodiment
[0085] FIG. 8 is a diagram showing a second embodiment of a
substrate processing apparatus according to the invention, and FIG.
9 is a block diagram which shows the control structure of the
substrate processing apparatus of FIG. 8. The second embodiment is
quite different from the first embodiment in that DIW is supplied
as a mist-generating nozzle 7 discharges minute droplets toward the
surface of the lower layer frozen film 13f for the purpose of
forming the upper layer frozen film, and the rinsing liquid
supplier 62 is replaced with a rinsing liquid supplier 620. The
rinsing liquid supplier 620 is different from the rinsing liquid
supplier 62 only in that it does not comprise the temperature
adjuster, but is otherwise identical in structure to the rinsing
liquid supplier 62. That is, DIW supplied to the substrate W from
the rinsing liquid supplier 620 for the purpose of forming the
lower layer liquid film is not cooled but is at room temperature.
The same parts as those of the first embodiment will be denoted at
the same reference symbols below.
[0086] A motor 71 is disposed at a place outward from the spin
chuck 2 in a circumferential direction. A rotary shaft 73 is
connected to the motor 71, an arm 75 extending horizontally is
connected to the rotary shaft 73, and the mist-generating nozzle 7
is attached to the end of the arm 75. When the motor 71 is driven
in accordance with an operation command from the control unit 4,
the arm 75 swings around the rotary shaft 73.
[0087] FIG. 10 is a plan view showing a movement of the
mist-generating nozzle. When the motor 71 is driven and the arm 75
swings in accordance with an operation command from the control
unit 4, the mist-generating nozzle 7 moves along a moving
trajectory T2 as shown in FIG. 10 while staying opposed to the top
surface Wf of the substrate W. The moving trajectory T2 is a
trajectory from a rotation center position Pc2 toward an edge
position Pe2. The rotation center position Pc2 is over the
substrate W and above the rotation center A0 of the substrate W,
and the edge position Pe2 is above the outer circumferential edge
of the substrate W. That is, the motor 71 relatively moves the
mist-generating nozzle 7 relative to the substrate W and parallel
to the top surface Wf of the substrate W. The mist-generating
nozzle 7 is further capable of moving to a stand-by position Ps2
which is on an extension of the moving trajectory T2 and off to the
side from its opposed position to the substrate W.
[0088] The mist-generating nozzle 7 is connected with the rinsing
liquid supplier 620. When the mist-generating nozzle 7 is arranged
at an opposed position to the top surface Wf of the substrate W and
the rinsing liquid supplier 620 supplies DIW to the mist-generating
nozzle 7, the mist-generating nozzle 7 discharges the DIW as minute
droplets toward the top surface Wf of the substrate W. When the
motor 71 moves the mist-generating nozzle 7 along the moving
trajectory T2 while the chuck rotating mechanism 22 rotates the
substrate W, with minute droplets of the DIW discharged from the
mist-generating nozzle 7 in accordance with an operation command
from the control unit 4, the minute droplets of the DIW are
supplied to the entire top surface Wf of the substrate W. In this
embodiment, the mist-generating nozzle 7 and the rinsing liquid
supplier 620 thus correspond to the "droplet supplier" of the
invention.
[0089] Next, a cleaning processing operation performed by the
substrate processing apparatus having the structure above will be
described with reference to FIGS. 11A through 11D and 12. FIGS. 11A
through 11D are diagrams showing processing to the top surface Wf
of the substrate W, FIG. 11A showing a lower layer liquid film
forming processing, FIG. 11B showing a lower layer liquid film
freezing processing, FIG. 11C showing an upper layer liquid film
forming and freezing processing, and FIG. 11D showing a frozen film
removal processing. FIG. 12 is a flow chart showing an operation
sequence of the substrate processing apparatus shown in FIG. 8.
[0090] FIGS. 11A and 11B are the same as FIGS. 5A and 5B, and Steps
S11 to S13 in FIG. 12 are the same as Steps S1 to S3 in FIG. 6.
Upon completion of the lower layer liquid film freezing processing
at Step S13, the control unit 4 activates the chuck rotating
mechanism 22 to rotate the spin chuck 2, positions the
mist-generating nozzle 7 to the rotation center position Pc2, and
gradually moves the mist-generating nozzle 7 toward the edge
position Pe2 of the substrate W while, by activating the rinsing
liquid supplier 620, discharging mist-like DIW as droplets toward
the top surface Wf of the substrate W from the mist-generating
nozzle 7, to thereby form the upper layer liquid film 12f at Step
S14. At the same time, the control unit 4 returns the cooling gas
discharge nozzle 3 to the rotation center position Pc after the
mist-generating nozzle 7 has left the rotation center position Pc2,
and while causing the cooling gas to be discharged from the cooling
gas discharge nozzle 3 toward the top surface Wf of the rotating
substrate W, gradually moves the cooling gas discharge nozzle 3
toward the edge position Pe2 of the substrate W. In consequence, as
shown in FIG. 11C, within the top surface Wf of the substrate W,
while the upper layer liquid film 12f is being formed, the frozen
area spreads from a central section of the top surface Wf of the
substrate W toward a peripheral section, whereby the upper layer
frozen film 14f is formed all over the top surface Wf of the
substrate W. Since the DIW forming the upper layer liquid film 12f,
although not cooled, is supplied as mist-like droplets to the
surface of the lower layer frozen film 13f, it is possible to
favorably form the upper layer frozen film 14f in a layered
structure without melting the lower layer frozen film 13f.
[0091] Whether the discharge of the mist-like DIW has finished is
then determined (Step S15), and Step S14 is continued when the
discharge has not finished yet (NO at Step S15), whereas the
operation proceeds to Step S16 when it is determined that the
discharge has finished since a predetermined time has elapsed for
example (YES at Step S15). During this, the control unit 4 can
adjust the film thickness of the upper layer liquid film 12f by
controlling the discharging time of the mist-like DIW from the
mist-generating nozzle 7.
[0092] The frozen film removal processing at Step S16 is identical
as Step S7 in FIG. 6, and FIG. 11D is the same as FIG. 5E. The
following Steps S17 to S19 are the same as Steps S8 to S10 in FIG.
6. In this embodiment, each one of Step S12, Step S13 and Step S14
thus corresponds to the "liquid supplying and freezing step" of the
invention, and these Steps S12 to S14 correspond to the
"multiply-layered frozen film forming step" of the invention.
Further, Step S16 corresponds to the "removal step" of the
invention.
[0093] As described above, according to this embodiment, since the
upper layer frozen film 14f is formed in a layered structure on top
of the lower layer frozen film 13f which is formed on the top
surface Wf of the substrate W and the frozen films 13f and 14f as a
whole are melted and accordingly removed as in the first embodiment
described earlier, it is possible to enhance the particle removal
rate while preventing damage upon the substrate W. In addition, the
lower layer frozen film 13f will not melt even without cooling of
the DIW, since, for the purpose of forming the upper layer frozen
film 14f in a layered structure, minute droplets of DIW are
discharged toward the surface of the lower layer frozen film 13f.
Therefore, the embodiment has an advantage that a structure for
cooling the DIW is unnecessary.
[0094] Further, in this embodiment, since the cooling gas discharge
nozzle 3 discharges the cooling gas while minute droplets of DIW
are discharged toward the surface of the lower layer frozen film
13f, it is possible to more securely prevent the lower layer frozen
film 13f from melting.
[0095] In other words, this embodiment comprises a droplet supplier
which discharges minute droplets of the liquid and accordingly
supplies the liquid toward the surface of the lower layer frozen
film. According to this structure, since minute droplets of the
liquid are discharged toward the surface of the lower layer frozen
film, an advantage is obtained that it is possible to prevent
melting of the lower layer frozen film even without cooling the
liquid by means of a temperature adjuster or the like for
instance.
[0096] Further, in this embodiment, the freezing of the liquid is
executed while the droplet supplier discharges minute droplets of
the liquid toward the surface of the lower layer frozen film.
According to this structure, since the liquid is frozen while the
droplet supplier discharges minute droplets of the liquid toward
the surface of the lower layer frozen film, it is possible to
favorably form a single layer of the upper layer frozen film on the
surface of the lower layer frozen film while preventing the lower
layer frozen film from melting without fail. At this stage, it is
possible to adjust the film thickness of the upper layer frozen
film by adjusting the liquid discharging time of discharging minute
droplets of the liquid from the droplet supplier for example.
[0097] <Others>
[0098] The invention is not limited to the embodiments described
above but may be modified in various manners in addition to the
embodiments above, to the extent not deviating from the object of
the invention. For instance, in the above first embodiment,
although the temperature adjuster 623 cools DIW supplied onto the
top surface Wf of the substrate W for the purpose of forming the
lower layer liquid film 11f, the invention does not demand cooling
of the DIW for forming the lower layer liquid film 11f. However,
since the lower layer frozen film 13f can be formed in a short
period of time if the DIW is cooled, cooling of the DIW is
preferable.
[0099] Further, in the above second embodiment, although at Step
S14 in FIG. 12, the cooling gas discharge nozzle 3 discharges the
cooling gas while the mist-generating nozzle 7 discharges minute
droplets of the DIW, this is not limiting. For example, as in the
first embodiment, after forming the upper layer liquid film 12f
with discharge of minute droplets of the DIW from the
mist-generating nozzle 7, the upper layer liquid film 12f may be
frozen with discharge of the cooling gas from the cooling gas
discharge nozzle 3 to thereby form the upper layer frozen film 14f
in a layered structure.
[0100] Further, in the embodiments above, the frozen films 13f and
14f are formed only on the top surface Wf of the substrate W.
However, the invention is not limited to this. The lower frozen
film may be formed also on the rear surface Wb of the substrate W
and the upper layer frozen film may be formed on the lower frozen
film in a layered structure. According to this modification, it is
possible to weaken the adherence between particles and the
substrate W not only at the top surface Wf of the substrate W but
also at the rear surface Wb of the substrate W. Hence, it is
possible to preferably remove particles from the rear surface Wb of
the substrate W.
[0101] Further, in the above first and the second embodiments,
although the liquid film 11f is formed on the top surface Wf of the
substrate W with the DIW which is discharged from the rinsing
liquid discharging nozzle 97 which is disposed at the under surface
of the blocking member 9, this is not limiting. FIGS. 13A to 13C
are diagrams showing a modification of discharge of the rinsing
liquid, FIG. 13A being a plan view, FIG. 13B being a cross
sectional view taken along the line B-B in FIG. 13A, and FIG. 13C
being a side view taken in the direction of the arrow C in FIG.
13A.
[0102] According to this modification shown in FIGS. 13A to 13C, a
discharge part 30 is disposed at the tip of the arm 35, and a
supply tube 60P is installed on the top surface extending from the
arm 35 to the discharge part 30. Disposed inside the supply tube
60P are a liquid supply pipe 62P which is communicated with the
rinsing liquid supplier 62 and a gas supply pipe 64P which is
communicated with the cooling gas supplier 64. In other words, the
liquid supply pipe 62P and the gas supply pipe 64P are disposed
side by side in the vicinity of each other. The cooling gas is
discharged at a gas discharge outlet 3A which is formed in the
discharge part 30 and is communicated with the gas supply pipe 64P,
whereas the DIW is discharged at a liquid discharge outlet 3B which
is formed near the gas discharge outlet 3A of the cooling gas
discharge nozzle 3 and is communicated with the liquid supply pipe
62P.
[0103] Since the liquid supply pipe 62P carrying the DIW is
disposed in the vicinity of the gas supply pipe 64P which carries
the cooling gas which is at such an extremely low temperature as
-100 degrees centigrade for example, this modification has an
advantage that the cold energy of the cooling gas works to prevent
the temperature of DIW which has been cooled down to a lower
temperature than room temperature by the temperature adjuster 623
from rising. Further, according to this modification, since the
liquid discharge outlet 3B for discharging the DIW is disposed in
the vicinity of the gas discharge outlet 3A for discharging the
cooling gas, it is possible to enhance the cooling effect exerted
upon the DIW by the cooling gas. In this modification, the gas
discharge outlet 3A thus corresponds to the "cooling gas
discharger" of the invention and the liquid discharge outlet 3B
thus corresponds to the "liquid discharge nozzle" of the
invention.
[0104] In other words, in this modification, the liquid supplier
includes a liquid supply pipe which supplies the liquid and a
liquid discharge nozzle which discharges the liquid inside the
liquid supply pipe toward the substrate, the freezing unit further
includes a gas supply pipe which guides the cooling gas to the
cooling gas discharger, and at least a part of the liquid supply
pipe and at least a part of the gas supply pipe are disposed side
by side in the vicinity of each other.
[0105] According to this structure, since at least a part of the
liquid supply pipe which supplies the liquid and at least a part of
the gas supply pipe which guides the cooling gas are disposed side
by side in the vicinity of each other, the liquid supplied to the
substrate flows near the cooling gas whose temperature is lower
than the freezing point of the liquid. Since the liquid supplied to
the substrate is accordingly cooled, melting of the lower layer
frozen film is prevented. At this stage, when the temperature of
the cooling gas is extremely low, about -100 degrees centigrade for
example, the cooling effect on the liquid which passes near the
cooling gas is very significant.
[0106] Further, in this modification, the liquid discharge nozzle
and the cooling gas discharger are disposed in the vicinity of each
other, and the relative moving mechanism relatively moves the
liquid discharge nozzle and the cooling gas discharger as one unit
relative to the substrate. According to this structure, the liquid
discharge nozzle and the cooling gas discharger disposed in the
vicinity of each other are relatively moved as one unit, and these
are always positioned close to each other. Consequently, when the
cooling gas discharger discharges the cooling gas, the coolness of
the cooling gas cools the liquid discharge nozzle. Hence, the
embodiment has an advantage that the melting of the lower layer
frozen film is more securely prevented.
[0107] Further, whole of the lower layer frozen film 13f and the
upper layer frozen film 14f which are formed on the top surface Wf
of the substrate W in a layered structure are removed by means of
the DIW supplied from the rinsing liquid supplier 62 in the above
first embodiment, and by means of the DIW supplied from the rinsing
liquid supplier 620 in the above second embodiment, respectively.
However, the invention is not limited to this. The frozen film may
be removed through chemical cleaning. FIG. 14 is a diagram showing
a modification in which a structure for chemical cleaning is added
to the apparatus of the first embodiment. FIG. 15 is a diagram
showing a frozen film removal processing in the apparatus shown in
FIG. 14. In this modification, the liquid supply pipe 25 is
connected also to a chemical solution supplier 61 in addition to
the rinsing liquid supplier 62. The chemical solution supplier 61
supplies a chemical solution such as an SCl solution (a liquid
mixture of aqueous ammonia and a hydrogen peroxide solution). The
apparatus is structured so that either one of the chemical solution
or DIW is selectively supplied to the liquid discharge nozzle 27
via the liquid supply pipe 25.
[0108] A motor 67 is disposed at a place outward from the spin
chuck 2 in a circumferential direction. A rotary shaft 68 is
connected to the motor 67, an arm 69 extending horizontally is
connected to the rotary shaft 68, and a chemical solution discharge
nozzle 6 is attached to the end of the arm 69. When the motor 67 is
driven in accordance with an operation command from the control
unit 4, the chemical solution discharge nozzle 6 moves in
reciprocation between a discharging position above the rotation
center A0 of the substrate W and a stand-by position away sideward
from the discharging position. The chemical solution discharge
nozzle 6 is connected to the chemical solution supplier 61 and
discharges the chemical solution supplied from the chemical
solution supplier 61 toward the top surface Wf of the substrate W
which is held by the spin chuck 2.
[0109] In this modification, after forming the frozen film in a
layered structure, the control unit 4 positions the chemical
solution discharge nozzle 6 at the discharging position and the SCl
solution is pressure fed into the chemical solution discharge
nozzle 6 and is supplied to the liquid discharge nozzle 27. This
causes the SCl solution to be supplied from the chemical solution
discharge nozzle 6 to the top surface Wf of the substrate W and
from the liquid discharge nozzle 27 to the rear surface Wb of the
substrate W. Since the zeta potential (electrokinetic potential) at
the surface of the solid matter in the SCl solution has a
relatively large value, when the area between the particles on the
top surface Wf of the substrate W and the top surface Wf of the
substrate W are filled with the SCl solution, significant repulsive
force acts between the particles and the top surface Wf of the
substrate W. This makes it even easier for the particles to fall
off from the top surface Wf of the substrate W and achieves
effective removal of the particles from the top surface Wf of the
substrate W. Further, in this modification, since the SCl solution
is supplied also to the rear surface Wb of the substrate W from the
liquid discharging nozzle 27, even when the contaminants adhere to
the rear surface Wf of the substrate W, it is possible to
efficiently remove the contaminants from the rear surface Wb of the
substrate W by means of the chemical cleaning effect of the SCl
solution. Further, in this modification, after cleaning with the
SCl solution, the DIW is supplied to the top surface Wf and the
rear surface Wb of the substrate W and rinsing with the DIW is
performed.
[0110] Meanwhile, in this modification, the cleaning with the SCl
solution as chemical cleaning which principally exerts a chemical
cleaning effect upon a top surface Wf of the substrate W is
executed. However, the chemical cleaning is not limited to the
cleaning with the SCl solution. For example, the chemical cleaning
may be wet cleaning which uses, as a processing liquid, an alkaline
solution, an acidic solution, an organic solvent, a surface active
surfactant or the like other than the SCl solution or wet cleaning
which uses a proper combination of these as a processing
liquid.
[0111] In the first embodiment described earlier, the rinsing
liquid discharging nozzle 97 discharges the DIW which is at room
temperature by stopping the operation of the temperature adjuster
623 to remove the frozen films 13f and 14f on the top surface Wf of
the substrate W at Step S7. However, a supply mechanism for
supplying the DIW at room temperature to the substrate may be
disposed separately. For example, a similar supply mechanism to the
chemical solution supplier 61 and the chemical solution discharge
nozzle 6 may discharge the DIW at room temperature to remove the
frozen films 13f and 14f.
[0112] Furthermore, the frozen films 13f and 14f formed on the top
surface Wf of the substrate W in a layered structure are removed by
the DIW in the above first and second embodiments. However, whole
of the multiply-layered frozen film may be removed through physical
cleaning instead. FIG. 16 is a diagram showing a modification in
which a structure for physical cleaning is added to the apparatus
of the first embodiment. FIG. 17 is a diagram showing a structure
of a two-fluid nozzle.
[0113] A motor 51 is disposed at a place outward from the spin
chuck 2 in a circumferential direction. A rotary shaft 53 is
connected to the motor 51, an arm 55 extending horizontally is
connected to the rotary shaft 53, and a two-fluid nozzle 5 is
attached to the end of the arm 55. When the motor 51 is driven in
accordance with an operation command from the control unit 4, the
two-fluid nozzle 5 swings around the rotary shaft 53.
[0114] This two-fluid nozzle 5 is a two-fluid nozzle of the
so-called external mixing type which collides a processing liquid
and a nitrogen gas (N2) in air (outside the nozzle) and generates
droplets of the processing liquid. In this modification, DIW
supplied from the rinsing liquid supplier 62 is used as the
processing liquid, and the nitrogen gas supplied from the drying
gas supplier 65 is used for instance. The two-fluid nozzle 5
includes a hollow body section 501. A processing liquid discharge
nozzle 502, which has a processing liquid discharging outlet 521,
is inserted inside the body section 501. The processing liquid
discharging outlet 521 is disposed at a top surface part 512 of an
umbrella part 511 of the two-fluid nozzle 5. Hence, supplied to the
processing liquid discharge nozzle 502, the processing liquid is
discharged toward the substrate W from the processing liquid
discharging outlet 521.
[0115] Further, a gas discharge nozzle 503 is disposed in the
vicinity of the processing liquid discharge nozzle 502, defining a
ring-shaped gas channel which surrounds the processing liquid
discharge nozzle 502. The tip end of the gas discharge nozzle 503
is tapered progressively thin, and the opening of this nozzle is
opposed against the substrate surface W. Hence, supplied to the gas
discharge nozzle 503, the nitrogen gas is discharged toward the
substrate W from the gas discharging outlet 531 of the gas
discharge nozzle 503.
[0116] The track of thus discharged nitrogen gas intersects that of
the DIW discharged from the processing liquid discharging outlet
521. That is, the liquid flow from the processing liquid
discharging outlet 521 collides with the gas flow at a collision
section G which is located within a mixing region. The gas flow is
discharged so as to converge at the collision section G. The mixing
region is a space at the bottom end of the body section 501. Hence,
the nitrogen gas colliding the DIW quickly changes the DIW into
droplets, immediately near the discharging direction in which the
DIW is discharged from the processing liquid discharging outlet
521. Cleaning droplets are generated in this manner.
[0117] Then, in this modification, after the frozen film is formed
in a layered structure, the control unit 4, with the blocking
member 9 located at the separated position, makes the two-fluid
nozzle 5 supply DIW droplets to the top surface Wf of the substrate
W while making the two-fluid nozzle 5 pivot over the substrate W.
This collides droplets with particles adhering to the top surface
Wf of the substrate W, and due to the kinetic energy of the
droplets, the particles are physically removed. This makes it easy
to remove particles off from the top surface Wf of the substrate W
and realizes excellent cleaning of the top surface Wf of the
substrate W.
[0118] Meanwhile, in this modification, the cleaning with droplets
using the two-fluid nozzle as physical cleaning which principally
exerts a physical effect upon the surface Wf of the substrate W is
executed. However, the physical cleaning is not limited to the
droplets cleaning. The physical cleaning may for example be scrub
cleaning which cleans the substrate W with a brush, a sponge or the
like brought into contact with the surface Wf of the substrate W,
ultrasonic cleaning which cleans the substrate W by vibrating and
separating particles adhering to the surface Wf of the substrate W
utilizing ultrasonic vibrations or by means of an action upon the
surface Wf of the substrate W by cavitations, air bubbles or the
like formed in a processing liquid, etc. Further alternatively,
whole of the multiply-layered frozen films may be removed off from
the top surface Wf of the substrate W through cleaning of the top
surface Wf of the substrate W which combines depending upon
necessity physical cleaning and chemical cleaning.
[0119] Further, in this modification, in executing a droplet
discharge from the two-fluid nozzle, the two-fluid nozzle of the
so-called external mixing type is used, but this is not limiting. A
two-fluid nozzle of the so-called internal mixing type may be used.
That is, a processing liquid may be mixed with gas inside the
two-fluid nozzle to generate droplets, and the droplets may be
discharged toward the substrate W at a discharging outlet of the
nozzle.
[0120] Further, the number of the layers in the upper layer frozen
film has the predetermined value in the first embodiment described
earlier. In the second embodiment described earlier, whether the
discharge of the DIW of minute droplets has finished or not is
determined in accordance with whether the predetermined time has
elapsed for example. These are controlled based on a stored count
or time within a memory incorporated inside the control unit 4 for
example. These count and time may be made changeable in the
invention. For instance, in the structure shown in FIG. 18, as a
modification of the first embodiment described earlier, a display
part 41 may show a message which requests for selection or entry of
the number of the layers in the upper layer frozen film, and the
upper layer frozen film may be formed in a layered structure with
the number of layers a user has operated an operation part 42 to
select or enter. Alternatively, as a modification of the second
embodiment described earlier, the display part 41 may show a
message which requests for selection or entry of minute droplets of
the DIW discharging time, and the discharge of minute droplets of
the DIW may be performed during the discharging time a user has
operated the operation part 42 to select or enter, to thereby form
the upper layer frozen film which has a desired film thickness.
According to the modification, it is possible to realize a
favorable substrate processing apparatus which meets various
substrate processing conditions such as the type of the substrate W
to be processed, the type of immediately preceding processing or
step executed upon the substrate W to be processed, and the recipe
of substrate processing executed upon the substrate W to be
processed. In the modification, the control unit 4 which
incorporates the memory thus corresponds to the "storage unit" of
the invention and the operation part 42 thus corresponds to the
"rewriting unit" of the invention.
[0121] In other words, the modification comprises a storage unit
which stores a number of times to form the upper layer frozen film
in a layered structure, and a rewriting unit which rewrites the
number of times stored within the storage unit in accordance with a
predetermined substrate processing condition. And, in the
modification, the forming of the upper layer frozen film in a
layered structure is executed the number of times stored in the
storage unit. According to this structure, while the upper layer
frozen film is formed in a layered structure the number of times
stored in the storage unit, this stored count is rewritten in
accordance with predetermined substrate processing conditions.
Therefore, the upper layer frozen film consisting of the number of
layers which corresponds to the substrate processing conditions is
formed in a layered structure. At this stage, the substrate
processing conditions may be, for instance, the type of the
substrate to be processed, the type of immediately preceding
processing or step executed upon the substrate to be processed, the
recipe of substrate processing executed upon the substrate to be
processed, and the like.
[0122] Further, in the embodiments above, although DIW is used as a
rinsing liquid which forms a liquid film, the rinsing liquid is not
limited to DIW. For instance, purified water, carbonated water, a
hydrogen-saturated water, and the like may be used as a rinsing
liquid which forms a liquid film.
[0123] Further, although the embodiments above have described an
example of applying the substrate processing apparatus which has a
function to freeze a liquid film formed on the surface Wf of the
substrate W according to the invention to cleaning processing to
remove contaminants, such as particles, adhering to the surface Wf
of the substrate W, the invention is not limited only to such an
application. For instance, a liquid film frozen by using the
substrate processing apparatus and method according to the
invention is used as a protection film to protect the substrate
surface. That is, a liquid film is formed on the top surface Wf of
the substrate W, and the liquid film is frozen so that the frozen
film function as a protection film of the top surface Wf of the
substrate W, thereby protecting the top surface Wf of the substrate
W against contamination from the ambient atmosphere around the
substrate W. This allows the substrate W to be stored or remain on
standby while preventing contamination of the top surface Wf of the
substrate W by the frozen film acting as a protection film.
[0124] The present invention is applicable to a substrate
processing apparatus and a substrate processing method which freeze
a liquid film formed on a surface of substrates in general
including semiconductor wafers, glass substrates for photomask,
glass substrates for liquid crystal display, glass substrates for
plasma display, substrates for FED (field emission display),
substrates for optical disks, substrates for magnetic disks, and
substrates for magnet-optical disks.
[0125] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed
in a limiting sense. Various modifications of the disclosed
embodiment, as well as other embodiments of the present invention,
will become apparent to persons skilled in the art upon reference
to the description of the invention. It is therefore contemplated
that the appended claims will cover any such modifications or
embodiments as fall within the true scope of the invention.
* * * * *